1. Technical Field
The present invention relates to a display device, a display control method, and a display system.
2. Related Art
There is a display device having the function of inputting various instructions using indicator such as an electronic pen or finger to a display area (see JP-A-2011-253306). With this function, various operations on an application such as scrolling up and down an application window, as well as drawing an image object on top of a background image (so-called annotation), can be carried out from a place which is distant from a computer controlling the display device. For example, in the state where a document preparation application or an application for displaying a presentation image is being executed, an annotation is drawn on top of a displayed image (background image), using an electronic pen. Thus, the viewer's attention is drawn to specific parts.
Here, if the content of the background image is changed, the annotation drawn thereon often needs to be erased. Generally, an annotation makes sense when a specific background image is situated at a specific position. Therefore, if this relationship is changed, the existence of the annotation no longer makes sense.
According to the related art, when the content of the background image is changed by scrolling up or down the window or by switching the application to another, generally, the user needs to carry out an operation for deleting the displayed annotation, using an indicator. It is troublesome to carry out this operation every time the background image is updated. In view of this, there is a technique that provides an application with the function of forcibly erasing the annotation drawn, when displaying a new page.
However, according to the related art, the automatic deletion of the annotation functions only in response to a specific operation in an application (specifically, change or update of an entire display image due to page switching) and does not function in the case where the display content is partly changed by scrolling up or down the window, or the like. Moreover, according to the related art, the automatic deletion does not function in the case where the content of the background image is changed with the annotation disabled as a result of carrying out an operation extending across a plurality of applications (switching the active application or the like).